Priority is claimed on Japanese Patent Application No. 2007-105727, filed on Apr. 13, 2007, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a cooling structure for batteries and electrical units.
2. Description of Related Art
A vehicle, which depends on a motor to obtain the entire driving force for traveling or a part of a driving force for traveling, such as an electric vehicle, a fuel cell vehicle, and a hybrid vehicle, is provided with a battery for driving the motor or high-voltage electrical units such as a drive circuit of the motor. Since the battery or the electrical units generate heat due to the characteristics thereof, the battery or the electrical units need to be cooled. In particular, the output performance of the battery of them significantly is affected by temperature. For this reason, the cooling of the battery is important to both the driving force of the motor and the traveling performance of a vehicle.
There has been the following structure as a cooling structure for a battery or high-voltage electrical units. In a casing of the structure, a battery is disposed on an upstream portion of the casing, and electrical units are disposed on a downstream portion of the casing so as to be divided from one another in the width direction of a vehicle. A cooling fan is provided on the upstream side of the battery, a duct of the cooling fan is connected to the front portion of the casing, and cooling air discharge ducts are provided on the rear side of the electrical units that are disposed on the left and right sides (see Japanese Unexamined Patent Application, First Publication No. H11-180168).
Further, there has been the following assembly structure. A battery is contained in a battery box, high-voltage electrical units are disposed on a rear upper surface of the battery box, a cooling air inlet is formed at a front portion of the battery box, a cooling air outlet is formed at a rear portion of the battery box, and a cooling fan is provided on an upstream side of the outlet (see Japanese Unexamined Patent Application, First Publication No. H7-156826).
However, there have been the following problems in the related art. That is, as a voltage of an electric power source trends to be increased in the above-mentioned various vehicles, there has been a limitation on a space where the battery is contained in the form of a group. For this reason, the battery should be divided into a plurality of batteries, which is connected to one another in series, in order to be mounted. When the plurality of batteries connected to one another in series is divided and disposed, for example, in a width direction of the vehicle, temperature of each of the batteries becomes imbalanced in the width direction of the vehicle. In this case, even though the batteries are connected to one another in series, some batteries are different from the other batteries in temperature. For this reason, there are problems in that it is difficult to equally charge the batteries or it is not possible to obtain sufficient output. That is, if some batteries are different from the other batteries in temperature, appropriate charging voltages of the batteries vary during the charging of the batteries. As a result, it is not possible to sufficiently charge the batteries.
For example, in the case of Japanese Unexamined Patent Application, First Publication No. H11-180168, if the cooling air is inhibited from flowing out from one cooling air discharge duct in the width direction of the vehicle, the cooling air hardly flows out on one side. As a result, the temperature of one battery rises. If the temperature of one battery becomes significantly higher than the temperature of the other battery, temperature difference partially occurs between the batteries that are divided and disposed on the left and right sides. For this reason, it is difficult to equally charge the batteries on the left and right sides. As a result, it is not possible to ensure sufficient output of the batteries.
In order to prevent this, the following is considered: a cooling fan is provided at each of the electrical units and batteries, and the temperature of each of the electrical units and the batteries is monitored, and only required portions are cooled by the cooling fans. However, since the cooling fan should be provided at each of the equipments in this case, there is a problem in that the weight and cost are increased.
In view of the above described circumstances, the present invention has an object of providing a cooling structure for batteries and electrical units that can cool a plurality of divided batteries so as to prevent temperature difference from occurring and can effectively cool electrical units.